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 Post subject: GT550 barrels
PostPosted: Sat Apr 21, 2018 4:09 pm 
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Moto GP
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Location: Illinois
Question for our GT550 experts. How many different designs of barrels were there? I know there were iron cast in liners and carbide plated barrles used on Euro models.

I need a left barrel for a friend's J model and the one I got from that auction site appears similar - but the fins are dramatically smaller. One has full fins above the intake ports and others do not. I checked on CMSNL and sure enough JK are one part umber and L were different, but I don't know which is which. I suspect that the later barrels had fins cut down to allow more space for the linked carbs with all the "stuff" on top of them.

And are the pistons all the same? The originals had solid skirts but replacements have three small cooling/lubrication holes to keep the intake port bridge happy. Was that a design change or supplier change?

Anyone know for sure?


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 Post subject: Re: GT550 barrels
PostPosted: Sat Apr 21, 2018 4:48 pm 
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Location: southwestern Pennsylvania
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A pic of my J-model cylinders is in my build topic: http://www.suzuki2strokes.com/forum/viewtopic.php?f=21&t=13106&start=0

The petcock is further back on the J/K models & the ram air covers are longer.
Image

The J/K cylinder head is also a lot different from the later models.

Post pics or links if you don’t figure it out & I’ll compare them to my cylinders.

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BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE


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 Post subject: Re: GT550 barrels
PostPosted: Sat Apr 21, 2018 6:10 pm 
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Thanks. That all makes sense. Do you know anything about pistons with holes in them?


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 Post subject: Re: GT550 barrels
PostPosted: Sat Apr 21, 2018 8:37 pm 
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Location: southwestern Pennsylvania
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No. I got Wiseco 1st over pistons for the GT550 build. And Wiseco 2nd over pistons for the T500 build.

I think the correct term for trying to do two spiffy cafe builds at the same time is money pit.

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BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE


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 Post subject: Re: GT550 barrels
PostPosted: Sat Apr 21, 2018 9:18 pm 
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Thanks. I believe you are correct with that nomenclature.

I'm less sure what the plural of that is for multiple projects at the same time. Let me google that.

Ah so. Google suggests that term used for doing more than two projects simultaneously is "insanity" :? :lol:


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 Post subject: Re: GT550 barrels
PostPosted: Sun Apr 22, 2018 5:16 pm 
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Location: The Republic of South Yorkshire
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Bikes owned: GT550s GT750 GSX1400 and lots of spares
Quote:
From tz375
Question for our GT550 experts. How many different designs of barrels were there? I know there were iron cast in liners and carbide plated barrles used on Euro models.

And are the pistons all the same? The originals had solid skirts but replacements have three small cooling/lubrication holes to keep the intake port bridge happy. Was that a design change or supplier change?

Anyone know for sure?


3 different types to my certain knowledge - I have each in the stash.
Later pistons had the 3 holes which made better piston/barrel lube.
Here's a pic of the different barrels at the rear.
Attachment:
Different 550 barrels.jpg
Different 550 barrels.jpg [ 329.03 KiB | Viewed 751 times ]

There were at least two and possible three different heads on the 550 and definitely three different RAM air cowls. Early J/K 'square' type, and then integral and separate 'RAM AIR' casting or 'badge' type. Last two interchanged.
If you use half of each of the later types, it really upsets the rivet counters. Although you may have to tell them first. :lol:


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 Post subject: Re: GT550 barrels
PostPosted: Mon Apr 23, 2018 3:33 pm 
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Thanks mate. Much appreciated.


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 Post subject: Re: GT550 barrels
PostPosted: Tue Apr 24, 2018 9:54 am 
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Road race school

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Bikes owned: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
That is a very narrow inlet tract on the Nikasil when compared to the iron liner one. Has the iron one been ported?


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 Post subject: Re: GT550 barrels
PostPosted: Tue Apr 24, 2018 10:53 am 
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World Superbike
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Joined: Thu Feb 16, 2012 11:50 am
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Location: The Republic of South Yorkshire
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Bikes owned: GT550s GT750 GSX1400 and lots of spares
Pass. It's just one of my stock!


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 Post subject: Re: GT550 barrels
PostPosted: Sat Apr 28, 2018 9:00 am 
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Expert racer

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Location: New Hampshire
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Bikes owned: Suz, Yam, Honda, Kaw.
sportston wrote:
That is a very narrow inlet tract on the Nikasil when compared to the iron liner one. Has the iron one been ported?


I would say yes.


Alan H,

How easy it to find the Nikasil ones in Europe? I have seen cases in USA cut out wider for this but we never got that model here.

Did they change the exhaust port height/dimension vs cast (Can you check against the non-ported cylinder). I think they did not but not sure.... they did on the GT250A.

Possible 4th Cylinder difference:
There may be a fourth style but would apply to the later cast iron. I recently purchased a set of GT380 later style (GT380 early/late had similar casting design concept changes as the gt550) and there was no opening for the SRIS hose. Clearly factory changed casting and removed. When was this done 1977? Did this also occur on GT550 also?

That is OK I cut them off since to me that tube stuck in the middle of the little gt380 transfer port must causes a little disturbances, be it trivial or not, versus the other side. On the GT550 Nikasil one it looks like Suz moved this passage to the new secondary transfer port.

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76 GT250 (T350 upgrade),
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77 Yamaha RD400 (Daytona Cyls),


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